Method and system to determine an optimal tissue compression time to implant a surgical element

ABSTRACT

An apparatus for determining an optimal amount of tissue compression for applying a surgical element to tissue is disclosed. The apparatus includes a device for compressing tissue which supports a measuring device adapted to detect a tissue parameter upon the compression of tissue. The measuring device communicates with an indicator. Upon compressing tissue, when the measuring device determines that the compressed tissue parameter reaches a predetermined threshold, the measuring device sends a signal to the indicator such that the indicator provides an indication to a surgeon that the threshold has been reached. The measuring device may include a load cell and the tissue parameter may be a viscoelastic reactive force of the tissue per unit time.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

The instant patent application is a divisional of U.S. patentapplication Ser. No. 11/409,154, now U.S. Pat. No. 8,062,236, filed Apr.21, 2006 which claims priority to U.S. Provisional Patent ApplicationSer. No. 60/764,451 and U.S. Provisional Patent Application Ser. No.60/764,449, both to Michael A. Soltz filed on Feb. 2, 2006. Each ofthese applications is incorporated herein by reference in its entirety.U.S. patent application Ser. No. 11/408,492 to Michael A. Soltz entitled“Mechanically Tuned Buttress Material to Assist with Proper Formation ofSurgical Element in Diseased Tissue” filed contemporaneously with U.S.Pat. No. 8,062,236 is also incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure is directed to surgical stapling devices andsutures and, in particular, to methods and devices for providing anoptimal amount of compression to the tissue for an optimal formation ofthe staples and sutures.

2. Description of the Related Art

Anastomosis is the surgical joining of separate hollow organ sections.Typically, an anastomotic procedure is performed during surgery in whicha diseased or defective section of hollow tissue is removed. Theanastomotic procedure joins or connects the remaining end tissuesections after the diseased tissue is removed. Depending on the desiredanastomosis procedure, the end sections may be joined by eithercircular, end-to-end or side-to-side organ reconstruction methods.

In a known circular anastomotic procedure, a stapling device joins twoends of an organ section together. The stapling device can drive acircular array of staples through the end of each organ section. Thedevice can simultaneously core any tissue interior of the drivencircular array of staples to free a tubular passage. Many examples forperforming circular anastomosis of hollow organs are described in U.S.Pat. Nos. 6,959,851, 6,053,390, 5,588,579, 5,119,983, 5,005,749,4,646,745, 4,576,167, and 4,473,077, which are incorporated by referenceherein in their entirety.

Typically, these devices include an elongated shaft having a handleportion at a proximal end thereof to effect actuation of the device. Thedevice also has a staple holding component disposed at a distal endthereof. An anvil assembly including an anvil rod with an attached anvilhead is mounted to the distal end of the device. The anvil is adjacent astaple holding component. Opposed end portions of tissue of the holloworgan(s) to be stapled are clamped between the anvil head and the stapleholding component. The clamped tissue is stapled by driving one or morestaples having a predetermined size from the staple holding component.In this manner, the ends of the staples pass through the tissue and aredeformed by the anvil head. An annular knife is advanced to core tissuewithin the hollow organ. In this manner, the knife clears a tubularpassage within the organ.

Surgical stapling devices for performing circular anastomosis have alsobeen used to treat internal hemorrhoids in the rectum. During the use ofa circular stapling device for hemorrhoid treatment, the anvil head andthe staple holding component of the surgical stapling device areinserted through the anus and into the rectum with the anvil head andthe staple holding component in an open or un-approximated position.Thereafter, a suture is used to pull the internal hemorrhoidal tissueand/or mucosal tissue towards the anvil rod. Next, the anvil head andthe staple holding component are approximated to clamp the hemorrhoidaltissue and/or mucosal tissue between the anvil head and the stapleholding component. The stapling device is fired to remove thehemorrhoidal tissue and/or mucosal tissue and staple the cut tissue.Sutures are also known in the art to connect or join tissue.

Although the use of circular anastomosis staplers for hemorrhoidtreatment has many benefits, often a surgeon will encounter one or moredifferent types of tissue in the body for which to apply a surgicalelement such as a staple.

Some other tissue types include cardiac tissue, gastrointestinal tissue,and pulmonary tissue. In these different types of tissues, there may bea number of different other types of classes of such tissue, such asischemic tissue, or diseased tissue, thick tissue, tissue treated withmedicines or compounds, diabetic tissue, as well as numerous others.

Of utmost concern to surgeons is to ensure proper formation of therespective surgical element (such as the array of staples) into suchtissue. It has been observed that with certain types of tissue such asischemic tissue, or diabetic tissue an improved surgical outcome mayoccur after an amount of compression is applied to the tissue for anoptimal time period.

However, further compression for a time period (after an optimal timeperiod) is not favored. However, in the surgical environment, it isdifficult to visually or audibly appreciate the optimal amount ofcompression that should be applied to the various tissue types, and alsoit is difficult to visually or audibly appreciate the optimal timeperiod for tissue compression.

Accordingly, a continuing need exists in the art for a device for thetreatment of tissue which can quickly and easily compress tissue priorto applying a surgical element in the tissue for an optimal time period.It is a further need in the art for a device that can compress tissueand then communicate an indication to the surgeon that a threshold hasbeen reached and that the surgical element should be applied to thetissue for proper formation of the surgical element such as a staple ora suture.

SUMMARY

According to an aspect of the present disclosure, there is provided amethod for determining an optimal compression of tissue to apply asurgical element. The method has the step of applying a load to thetissue. The method also has the step of determining a reactive loadapplied by the tissue in response to the load. The method further hasthe step of determining the reactive load per unit time for apredetermined time period and determining a slope of the reactive loadper unit time. The method further has the steps of evaluating the sloperelative to a predetermined threshold, and signaling when the slopeexceeds the predetermined threshold.

According to another aspect of the present disclosure, there is providedan apparatus for determining an optimal amount of tissue compressionprior to the insertion of a surgical element into the tissue. Theapparatus has a measuring device configured to detect a tissue parameterupon the compression of the tissue. When the measuring device reaches athreshold after the tissue is compressed for a predetermined timeperiod, an indicator indicates to the surgeon the event of the thresholdand that the surgical element is ready to be inserted to the compressedtissue. The threshold is indicative of the surgical element beingproperly formed in the tissue at the indicated time period. When thecompression is lifted after the threshold, the tissue with the surgicalelement returns to a substantially an uncompressed state withoutnecrosis.

According to yet another aspect of the present disclosure there isprovided a method for determining an optimal compression of tissue toapply a surgical element. The method has the steps of measuring aninitial tissue thickness and applying a load to the tissue. The methodalso has the steps of determining a physiological event of the tissue inresponse to the load applied and measuring the thickness at the event.The method also modulates a surgical instrument in response to thethickness at the event.

According to another aspect of the present disclosure there is provideda device for determining an optimal amount of compression of tissue toapply a surgical element. The device has a body with a handle assemblyconnected to a shaft, and a load cell assembly with a load cell. Thedevice also has a movable platen and a stationary platen connected tothe shaft. The movable platen compresses the tissue between thestationary platen to apply a load to the tissue. The load cell isdisposed in contact with the movable platen to determine a reactive loadapplied by the tissue in response to the load. The device also has acontroller configured to determine the reactive load per unit time for apredetermined time period.

According to a further aspect of the present disclosure, there isprovided an apparatus to determine an optimal amount of strain on tissueto apply a surgical element. The apparatus has a first caliper arm and asecond caliper arm and a body connected to the first caliper arm and thesecond caliper arm. The distance between the first caliper arm and thesecond caliper arm is measured as a gap. The first caliper arm ismovable with respect to the second caliper arm and is adapted to move ina direction toward to the second caliper arm to measure an initialtissue thickness in the gap. The first caliper arm and the secondcaliper arm can further move toward one another to apply a load to thetissue to compress the tissue to a predetermined tissue thickness. Thepredetermined tissue thickness corresponds to the optimal amount ofstrain on the tissue suitable to apply the surgical element into tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a perspective view of a device for implanting a surgicalelement into tissue;

FIG. 2 is a schematic illustration of a first tissue section beingcompressed to a second tissue section according to an embodiment of thepresent disclosure with the tissue responding by imparting a reactionforce in response to the compression;

FIG. 3 is a plot of a predicted force versus time for a rapid loadingcompression of gastrointestinal tissue for a 1.5 mm gap distance withthe plot showing the equilibrium state of the viscoelastic tissue;

FIG. 3A is a view of tissue being between a moveable platen and astationary platen showing the tissue having an initial tissue thickness;

FIG. 3B is a view of tissue being compressed between a moveable platenand a stationary platen showing the tissue having an final gapthickness;

FIG. 3C is a plot of the equilibrium force of the tissue versus thetime;

FIG. 3D is a plot of a variation of the tissue thickness versus time;

FIG. 3E is a plot of the initial and hemostasis thickness for varioustissues;

FIG. 4 is an illustration of a system for determining an optimalcompression time with the system having a movable platen, a stationaryplaten and a load cell according to the present disclosure;

FIG. 4A is an illustration of a manual system for determining an optimalcompression time with the system having a movable platen, a stationaryplaten, a load cell, and a display screen;

FIGS. 5 and 6 are perspective views of the system with the load cell andmovable platen compressing the tissue with FIG. 5 showing a mechanicalloading of the tissue and FIG. 6 showing tissue clamped between thejaws;

FIG. 7 shows a schematic block diagram according to a method of thepresent disclosure for compressing tissue to determine an optimal amountof compression and a optimal time for which to implant a surgicalelement into the tissue;

FIG. 8 is a caliper device for determining an initial tissue thicknessand a hemostasis thickness of the tissue;

FIGS. 9 and 10 shown the caliper device of FIG. 8 determining theinitial tissue thickness and the hemostasis thickness of the tissue;

FIG. 10A is a plot of a percentage amount of compressive strain appliedto tissue for several different tissue types;

FIG. 11 is an illustration of a tissue section with various sequentialdegrees of compressive strain applied to the tissue section and theresult on the tissue section at each strain increment;

FIGS. 12A and 12B show an example of a small intestine histology with nostrain applied and with strain applied to the tissue; and

FIG. 13 shows a schematic block diagram according to a method of thepresent disclosure for measuring an initial tissue thickness of tissuefor determining the hemostasis tissue thickness for one or more surgicalparameters of the procedure.

DETAILED DESCRIPTION

Embodiments of the presently disclosed method, apparatus and system willbe described herein below with reference to the accompanying drawingfigures wherein like reference numerals identify similar or identicalelements. In the following description, well-known functions orconstructions are not described in detail to avoid obscuring thedisclosure in unnecessary detail.

Referring to FIG. 1, there is shown a device for applying a surgicalelement to tissue. This device is described in U.S. Pat. No. 6,959,851.In one embodiment, the device is a stapling device 10 having a proximalhandle assembly 12, a central body portion 14 and a distal head portion16.

The proximal handle assembly 12 has a rotatable approximation knob 18and a firing trigger 20. The approximation knob 18 is operable to moveanvil 22 in relation to shell assembly 24 of head portion 16 betweenspaced and approximated positions and firing trigger 20 is operable toeject surgical elements (fasteners) from shell assembly 24 and advance aknife blade through shell assembly 24 to cut tissue.

In gastrointestinal surgery, the goal of the surgery is to provide for ahemostatic leak free joint by mechanically compressing the tissue.However, various tissue specific considerations may exist that caneffect blood perfusion to the anastomotic wound. Some considerationsinclude poor blood supply, ischemia, diabetes, tissue thickness, andpoor fluid flow through the tissue.

In one aspect the present disclosure provides for a method of improvedstaple formation to give surgeons more flexibility in the surgicalenvironment. The improved staple formation provides that two or moredesired sections of tissue can be joined to achieve acceptable andproper staple formation and whereas the two joined tissue sections willbe permanently joined and heal without any leakage.

FIG. 2 shows a first discrete tissue section 30, and a second discretetissue section 32. Each has various layers such as longitudinal muscle,circumferential muscle, sub mucosa, and mucosa. The present methodprovides for determining an optimal amount of compression to the twotissue sections 30, 32, prior to introducing any surgical element inorder to pre-treat the tissue sections. Thereafter, only after thetissue sections 30, 32 have been pretreated with the optimal amount ofcompression, are the two tissue sections 30, 32 ready to be joined bythe surgical element.

In one example, the first tissue section 30 will be compressed at thesame time as the second tissue section 32. In another example, each ofthe tissue sections 30, 32 may be individually compressed with theoptimal amount of compression. In still another embodiment, tissuesections (not shown) may be compressed in a radial manner with theoptimal amount of compression, and then joined with an array of surgicalelements. Various configurations are possible and within the presentdisclosure.

According to another aspect of the present disclosure, the insertion ofa surgical element such as a staple for proper staple formation can bethought of as a stress relaxation experiment. Stress relaxation withviscoelastic materials is achieved when a force from the tissue does notchange per unit time, or changes negligibly over time.

In this aspect, the tissue is loaded between a first platen 120 and asecond platen 122 as shown in FIGS. 5 and 6 which will be discussed indetail hereafter. The moveable platen 120 is actuated to compress thetissue to a desired final thickness. As shown in FIG. 2, during a timeperiod of the compression, the tissue resists the deformation by thetissue exerting a reaction force Ft in response to the compression forceon the tissue F.

In viscoelastic materials, faster compression creates greater reactionforces. The model of stress relaxation is based on Fung's Quasi-LinearViscoelasticity Theory. For a tissue specimen of biological tissuesubjected to compressive deformation, if a step increase in compressionis made on the tissue specimen, the stress developed will be a functionof time (t), and the strain (ε).

The history of the stress called the relaxation function, K(ε, t) willbe of the form of:K(ε,t)=G(t)T ^(ε)(ε)  Equation (1)

Where G(t) is the reduced relaxation function, and represents thenormalized function of time, and T(ε) is the elastic response of thetissue. It is assumed that the stress response to a change in straindε(t), superimposed on a specimen in a state of strain ε at time twhere:

$\begin{matrix}{{G\left( {t - \tau} \right)}\frac{\partial{T^{e}\left\lbrack {ɛ(\tau)} \right\rbrack}}{\partial ɛ}{\partial{ɛ(\tau)}}} & {{Equation}\mspace{14mu}(2)}\end{matrix}$

The total stress T(t), is given by:

$\begin{matrix}{{T(t)} = {\int_{- \infty}^{t}{{G\left( {t - \tau} \right)}\frac{\partial{T^{e}\left\lbrack {ɛ(\tau)} \right\rbrack}}{\partial ɛ}\frac{\partial{ɛ(\tau)}}{\partial\tau}\ {\mathbb{d}\tau}}}} & {{Equation}\mspace{14mu}(3)}\end{matrix}$

Therefore, the total stress at time t is the sum of contributions of allof the past changes, with the same reduced relaxation function.

When the force is applied at the tissue at time t=0, and σ_(v)=ε_(v)=0for t<0

Then Equation 3 reduces to:

$\begin{matrix}{{T(t)} = {{{T^{e}\left( 0^{+} \right)}{G(t)}} + {\int_{0}^{t}{{G\ \left( {t - \tau} \right)}\frac{\partial{T^{e}\left\lbrack {ɛ(\tau)} \right\rbrack}}{\partial\tau}{{\mathbb{d}\tau}.}}}}} & {{Equation}\mspace{14mu}(4)}\end{matrix}$

And if, ∂T^(ε)/∂t, ∂G/∂t are continuous, then the above equation isequivalent to:

$\begin{matrix}\begin{matrix}{{T(t)} = {{{G(0)}{T^{e}(t)}} + {\int_{0}^{t}{{T^{e}\left( {t - \tau} \right)}\frac{\partial G}{\partial\tau}\ {\mathbb{d}\tau}}}}} \\{= {\frac{\partial}{\partial t}{\int_{0}^{t}{{T^{e}\left( {t - \tau} \right)}{G(\tau)}\ {{\mathbb{d}\tau}.}}}}}\end{matrix} & {{Equation}\mspace{14mu}\left( {5,6} \right)}\end{matrix}$

In the Laplace Domain, the total stress is given by:

$\begin{matrix}{{\overset{\_}{T}(s)} = {{L\left\{ {T(t)} \right\}} = {\int_{0}^{\infty}{{T(t)}{\mathbb{e}}^{{- s}\; t}\ {\mathbb{d}t}}}}} & {{Equation}\mspace{14mu}(7)}\end{matrix}$

Applying this transformation to T(t), in Equation 6, the total stressis:

$\begin{matrix}\begin{matrix}{{\overset{\_}{T}(s)} = {L\left\{ {\frac{\partial}{\partial t}{\int_{0}^{t}{{T^{e}\left( {t - \tau} \right)}{G(\tau)}\ {\mathbb{d}\tau}}}} \right\}}} \\{\equiv {L\left\{ {\frac{\partial}{\partial t}\left\lbrack {{T^{e}(t)}*{G(t)}}\  \right\rbrack} \right\}}}\end{matrix} & {{Equation}\mspace{14mu}(8)}\end{matrix}$

For a general function f(t), the transformation of the first derivativedf/dt is calculated asL{df/dt}=sF(s)−f(0⁻),

Similarly, the transformation of the convolution in Equation 8 is:T (s)=s T ^(ε)(s) G (s)−T ^(ε)(0⁻)G(0⁻)  Equation (9)

The reduced relaxation function G(t), has been readily used to describethe behavior of biological tissues and is defined as:

$\begin{matrix}{{G(t)} = \frac{1 + {c\left\lbrack {{E_{l}\left( \frac{t}{\tau_{2}} \right)} - {E_{l}\left( \frac{t}{\tau_{1}} \right)}} \right\rbrack}}{1 + {c\;{\ln\left( \frac{\tau_{2}}{\tau_{1}} \right)}}}} & {{Equation}\mspace{14mu}(10)}\end{matrix}$

Where E1(z) is the exponential integral function defined by theequation:

${{E_{l}(z)} = {\int_{z}^{\infty}{\frac{{\mathbb{e}}^{- 1}}{t}\ {\mathbb{d}t}}}},\left( {{{\arg\; z}} < \pi} \right)$

Therefore G(s) is given by:

$\begin{matrix}{{{\overset{\_}{G}(s)} = {\frac{G(\infty)}{s}\left\{ {1 + {c\;{\ln\left\lbrack \frac{\left( {1 + {s\;\tau_{2}}} \right)}{\left( {1 + {s\;\tau_{1}}} \right)} \right\rbrack}}} \right\}}}{{and},}} & {{Equation}\mspace{14mu}(11)} \\{{G(\infty)} = \left\lbrack {1 + {c\;{\ln\left( \frac{\tau_{2}}{\tau_{1}} \right)}}} \right\rbrack^{- 1}} & {{Equation}\mspace{14mu}(11)}\end{matrix}$

In the current analysis, it is assumed that the elastic response is alinear function of strain,T ^(ε)(ε(t))=As(t)

Although biological tissues generally posses non-linear stress-straindependence, the current linear formation is sufficient to curve fit theresponse or force imposed by the tissue tested at one level ofcompression. This, from equation 9 listed above, it is observed that thetotal stress in the Laplace Domain is:

$\begin{matrix}{{\overset{\_}{T}(s)} = {A\; L\left\{ {ɛ(t)} \right\}{G(\infty)}\left\{ {1 + {c\;{\ln\left\lbrack \frac{\left( {1 + {s\;\tau_{2}}} \right)}{\left( {1 + {s\;\tau_{1}}} \right)} \right\rbrack}}} \right\}}} & {{Equation}\mspace{14mu}(12)}\end{matrix}$

Where A is the elastic stiffness of the tissue, c represents therelaxation index, τ1 is the short relaxation constant, and τ2 is thelong relaxation constant.

In Equation 12, L(ε(t)) represents the Laplace Transform of the appliedstrain function. The total stress T (t) can be determined numerically bycalculating the inverse Laplace Transform of T(s).

Referring now to FIG. 3, there is shown the predicted force of thetissue in response to the compression of the movable platen 120 shown inFIGS. 5 and 6 for rapid loading compression of a surgical element totissue. In this embodiment, the tissue is gastrointestinal tissue;however, the present analysis can be extended to other tissue types. Inthe embodiment shown in FIG. 3, the tissue is compressed to about 1.5 mmto have an equivalent instrument gap distance as measured between theanvil and the cartridge of a surgical stapler.

The model described above is an algorithm to determine the materialproperties of tissue including the Viscoelastic Index (c), the shorttime constant (τ1), and the long time constant (τ2) as well as theequilibrium modulus of the tissue (A). To apply this module to stapling,the reaction force Ft that is shown in FIG. 2 is determined. By curvefitting this force Ft response, the material properties of the specifictissue can be extracted for this individual patient, and the optimalamount of compression and time of compression for the individual patientcan be determined.

The model can also be used to predict behavior of the tissue 30, 32 whenstapled under various conditions such as rapid or slow compression asshown in FIG. 3. As is understood in FIGS. 3A and 3B, the tissuedisposed between a first platen 120 and a second platen 122 with have aninitial tissue thickness as shown in FIG. 3A, and then will becompressed to a final gap thickness as shown in FIG. 3B; however thetissue will impart a reaction force as discussed herein.

Referring now to FIG. 3, as can be seen the x-axis is time in seconds.The y-axis shows the reaction force of the tissue in pounds in responseto the compression. The y-axis can alternatively be measure in otherincrements such as Newtons.

As can be understood, the tissue exerts a peak force 33 immediatelywithin 100 seconds of about 80 pounds. This peak force 33 is not theideal time for this specific tissue sample to apply the desired surgicalelement based on the amount of compression that is exerted on thetissue. Thereafter, as time elapses to 200 seconds, the reaction forceis about 40 pounds. Thereafter, as further time elapses to 300 secondsthe reaction force is about 30 pounds. Thereafter, as further timeelapses to 400 seconds the reaction force is about 22 pounds.Thereafter, as further time elapses to 500 seconds the reaction force isabout 20 pounds. Further, as more time elapses to 600 seconds thereaction force is still and remains at about 20 pounds.

Thus, it is observed from FIG. 3, that the proper time to apply thesurgical element is at the equilibrium state 34 or when the slope of thecurve (of the reaction force over time) approaches a predeterminedthreshold or when the slope has a negligible change per unit time asshown by reference numeral 34. The reaction force exerted by the tissueat this point is called the equilibrium force 34. In one embodiment, theslope may arrive at zero. At another embodiment, the slope may bemarkedly less relative to the slope at 100 seconds from when compressionis initially applied to tissue. In another embodiment, the slope maysimply arrive and be maintained at a predetermined value or threshold.Various configurations are possible and within the scope of the presentdisclosure.

Referring now to the plot shown as FIG. 3C, there is shown a plot of theequilibrium force of the tissue over time. In the plot shown as FIG. 3C,it is understood that the equilibrium force imparted by the tissuedecreases over one hour as shown in T6. In this plot, tissue wascompressed for ten minutes and then allowed to rest without compressionfor ten minutes in a repeated cycle for one hour. The tissue wastransected and cut from all blood supply and fluid supply for theexperiment. Due to the compression over the time period the stiffness ofthe tissue decreased as shown in FIG. 3C. Over the elapsed time thetissue was perceived to be softer.

Referring now to the plot shown as FIG. 3D, there is shown a plot of thethickness of the tissue over time. In the plot shown as FIG. 3D, it isunderstood that the thickness of the tissue shown in millimetersincreases over the shown time period by about nearly 75 percent. It wasobserved that due to the compression, tissue thickness increases duepossibly to the spasmodic effect of the tissue to encourage blood orfluid to return to and traverses through the tissue.

Referring now to the plot shown as FIG. 3E, there is shown a plot of theinitial thickness of the tissue over time, and the thickness of thetissue where hemostasis is observed to occur. In the plot shown as FIG.3E, it is understood that for different tissue types such as lungtissue, colon tissue, stomach tissue, and small intestinal tissue, andamount of compression to a determined hemostasis thickness of tissue canalso collapse the blood vessels to assist with hemostasis, and will bediscussed in detail below.

Referring now to FIG. 4, there is shown the device 100 for measuring themechanical properties of the tissue. The device 100 has a handleassembly 102, and a shaft assembly 104. The shaft assembly 104 isconnected to the handle assembly 102. The shaft assembly 104 also has aload cell assembly 106. The load cell assembly 106 includes a transducerwhich converts a force into a measurable electrical output. The loadcell assembly 106 may be placed on various locations of the device 10and is shown between the movable platen 120 and a support plate 121 forillustration purposes only. The load cell assembly 106 may be placed inother locations such as those disclosed in United States PublishedPatent Application No. US 2005/0131390 to Heinrich, et al., which isherein incorporated by reference in its entirety. In one alternativeembodiment, the device 100 can be formed with a load cell 106 placed inor against the stationary platen 122.

In one embodiment, the load cell assembly 106 includes a strain gagebased load cell. In another embodiment, the load cell assembly 106 mayinclude a mechanical load cell assembly such as a hydraulic load cell,or a pneumatic load cell. Still alternatively, the load cell assembly106 may be a strain gauge load cell such as a bending beam load cell, ashear beam load cell, a canister load cell, a ring and so called“pancake load cell”, a button and washer load cell, or a helical orfiber optic load cell. Various configurations of the load cell assembly106 are possible and within the present disclosure, and it isappreciated that the load cell assembly 106 may be any device in orderto determine the force imparted by the tissue in response to thecompressive load.

The device 100 has a guide pin 108 and a rigid frame 110.Advantageously, the device 100 has a tissue gap insertion portion 112where several different tissue types may be easily inserted or placedbetween without regard to the thickness of the tissue or the tissuetype. In this aspect, the device 100 has a clamp bar 114 to clamp on thetissue. The device 100 also has a load cell assembly 106. The load cellassembly 106 is advantageously disposed between a movable platen 120 anda support plate 121. The support plate 121 is connected to the moveableplaten 120 by a first guide bar 123 and a second guide bar 125 to ensurelinear movement of the load cell as the moveable platen 120 is advanceddistally toward a stationary platen 122. Guide pin 108 connects with thesecond guide bar 125 and connects the plate 121 with the movable platen120.

The pusher 116 is adapted to place a know deformation on to the tissueby the moveable platen 122. The pusher 116 may be a piston or similarstructure and connected to a motor, or alternatively may be manuallyoperated. The moveable platen 122 contacts the load cell 106 that isdisposed between the plate 121 and the moveable platen 122. The loadcell 106 in contact with the moveable platen 122 simultaneously measuresthe reaction force of the tissue. The tissue has an initial thicknessthat is measured with a caliper or similar device and recorded. The loadcell assembly 106 is preferably disposed between the plate 121 and themovable platen 120. The moveable platen 120 and the stationary platen122 that are separated from one another by a selectable gap in thetissue gap insertion portion 112. The movable platen 120 isillustratively operatively connected to a motor M by a lead screwassembly 126. Although, illustrated schematically, the motor M may beseparate from the device 100 or compact enough to be placed in the shaftassembly 104.

Another embodiment of the present disclosure is shown in FIG. 4A. Inthis embodiment, the device 100 is a more compact device than theembodiment of the FIG. 4, and instead of a motorized operation thedevice 100, the device 100 for measuring the mechanical properties ofthe tissue may be manually operated. The device 100 may not be connectedto any external devices as in FIG. 4, but instead be suited for moredynamic working conditions. Again, the device 100 has a handle assembly102, and a shaft assembly 104. The shaft assembly 104 is connected tothe handle assembly 102 and also has a load cell assembly 106 beingdisposed between the plate 121 and the moveable platen 120.

The load cell assembly 106 includes a transducer which converts a forceinto a measurable electrical output. The load cell assembly 106 also hascircuitry that is adapted to convert a format of the output to displaythe output on a screen 101. The pusher 116 is adapted so the moveableplaten 120 places a know deformation on to the tissue. The moveableplaten 120 will further contact the load cell assembly 106 to measurethe reaction force. The tissue has an initial thickness that is measuredwith a caliper or similar device and recorded. The load cell assembly106 contacts the movable platen 120 that is separated from thestationary platen 122 by the selectable gap in the tissue gap insertionportion 112. In this embodiment, the movable platen 120 is connected tothe drive screw 126, and the surgeon can manually advance the movableplaten 120 distally in a direction toward the stationary platen 122using actuator 127. Once the displayed force on the screen 101 changesnegligibly per unit time, or alternatively stops changing per unit timethe surgeon will know that the tissue has reached the equilibrium state,and it is the correct time to implant the surgical element. The device100 may optionally not display the force on the screen 101 and insteadbe formed with an alarm that signals the surgeon that the tissue hasreached the equilibrium state. Various configuration and possible andare within the present disclosure.

Referring now to FIGS. 5, and 6, there is shown the device 100 of FIG. 4in operation. The initial thickness is measured when there is little orno load on the tissue T. Thereafter, the load cell assembly 106 has themovable platen 120 moving toward the stationary platen 122 to compressthe tissue T (as shown in FIG. 6) to apply a predetermined load on thetissue. The reaction force from the tissue and the displacement of thetissue are recorded by the load cell assembly 106 until the desiredfinal thickness is reached. Once reached, and the tissue T has reachedsubstantially an equilibrium state, the device 100 will signal an alarmthat the optimal compression time has been reached, and that a surgicalelement may be introduced through the tissue. The equilibrium state isdefined as the zero slope of the curve as shown in FIG. 3, or a statethat the tissue enters when the tissue reactive force per unit time isabout zero or changes negligibly per unit time.

FIG. 6 shows the tissue T disposed between the movable platen 120 andthe stationary platen 122. Given the viscoelastic properties of thetissue T, it is understood that it is desirable to compress the tissueuntil the slope of the tissue reaction force per unit time reaches zeroor a negligible amount after being compressed for a period of time. Theload cell assembly 106 communicates electronic signals from the loadcell assembly to a controller 124 shown schematically in FIG. 4.

The controller 124 of the device includes programmable instructions andwill monitor one or more parameters of the procedure. In one embodiment,the controller 124 may have a control system may include one or moredigital signal processors and a control module executable on theprocessor(s). The digital processor(s) and/or control module may includeone or more digital signal processors (DSP) and associated circuitry.The controller 124 may further include circuitry including analog,digital and/or logic devices (not explicitly shown). The DSPs may beupgradeable using flash ROM as is known in the art. Upgrades for theDSPs may be stored on computer readable media such as compact flashmedia, magnetic disks, optical disks, magnetic tape, or other suitablemedia so as to be compact. Furthermore, the controller 124 may reside atleast partially on the remote processor. The DSPs could be replaced byany system capable of mathematic operations. In one such embodiment, thecontrol system 124 may be a field programmable gate array.

In one embodiment, the controller 124 measures the reaction force of thetissue with the load cell assembly 106 per unit time. It should beappreciated that after a point 34 as illustrated on the plot of FIG. 3,the reaction force does not change with time or changes only apredetermined amount over time. The device 100 has the load cellassembly 106 that detects the reaction force at a first time interval,and then sequentially to another or later second time interval. Thedevice 100 will further measure the force at a number of increments overa period of time. The controller 124 will then determine the slope ofthe curve of the reaction force over the period of time. The controller124 will then compare the slope of the curve to a threshold value. Ifthe controller 124 determines that the slope has exceeded the thresholdvalue, the controller 124 will control an audible alarm (not shown) tosignal to the surgeon that the tissue has reached the optimalcompression value, and that any further compression is unnecessary andthat the surgical element is ready to be introduced into the tissue forjoining the tissue sections together. In another embodiment, of thepresent disclosure, the device 100 may have a strain gauge instead ofthe load cell 106 to measure the reaction force of the load on thetissue. In still another embodiment, the device 100 may have a pressuregauge, instead of the load cell. Various configurations are possible andwithin the scope of the present disclosure.

In another embodiment of the present disclosure, the controller 124 mayreceive other parameters instead of deformation in order to calculatethe slope and compare the slope to the threshold. The controller 124 inone embodiment may measure distance, and/or velocity of the moveableplaten 120. The controller 124 may measure, the distance relative to apredetermined distance threshold, of for example eighty percentcompression of the initial thickness without any load being applied.Once threshold distance is achieved, the controller 124 controls theaudible alarm to signal the surgeon that the optimal amount ofcompression has been achieved and the surgical element should be appliedto the tissue.

Referring now to FIG. 7, there is show a schematic block diagram thatthe controller 124 of the device 100 may use in order to determine theoptimal compression time of the tissue prior to implanting a surgicalelement into the tissue. The method commences at step 130. At step 132,the method has the step of compressing the tissue to a desired gap.Thereafter, the method continues to step 134 and measures a reactionforce of the tissue in response to the compression. Thereafter, themethod may further have the step of recording the reaction force in amemory. The method then arrives at a decision block at step 136.

At decision 136, the method has the step of determining whether thereaction force is in a predetermined range. If the measured force isless than a minimum force, then the force is insufficient and the methodreturns to step 132 to compress the tissue to the desired gap.

At decision 136, if the measured force is greater than a maximum forceat step 136, then the force may be too great and method proceeds to step138 to stop the movable platen 120 and proceed to wait. If the measuredforce is greater than a minimum force at step 136, and the force is lessthan the maximum force, the method continues to decision step 138.

At step 138, the controller 124 will determine a slope of the change inthe reaction force over the change in time to determine a parameter. Atstep 138, the controller 124 will evaluate the parameter with regard toa predetermined threshold. In one embodiment, the predeterminedthreshold will be the slope of the plot shown in FIG. 3. In this manner,when the slope is zero, or at a negligible change shown by referencenumeral 34 on the plot, this indicates to the controller 124 that thetissue has reached a state that is indicative of optimal amount ofcompression of the viscoelastic tissue and the surgical element shouldbe introduced into the tissue to ensure proper formation of the surgicalelement at step 140.

Thereafter, if the controller 124 reaches the predetermined threshold,then the method proceeds to step 140 where the device 100 may have anaudible alarm, or a visual alarm to indicate that the surgeon shouldfire the surgical element such as a staple.

In another embodiment, if the controller 124 reaches the predeterminedthreshold, then the method proceeds to step 140 where the device 100 maybe connected to the firing mechanism of the stapler of FIG. 1 toautomatically fire the surgical element such as a staple into thetissue. If the controller 124 at step 138 does not reach thepredetermined threshold, then the method proceeds back to step 134 wherethe device 100 may continue to apply compression on the tissue, andmeasure the reaction force of the tissue over time. It should beappreciated that in no instance is the tissue compressed for more thantwenty minutes at this may lead to excessive compression and inadequateblood flow to the tissue. The controller 124 has program instructions torelease the tissue if compressed for more than an allotted time periodsuch as twenty minutes.

In yet another embodiment of the present disclosure, the device 100 maymeasure a velocity or an acceleration of the moveable platen 120. Thecontroller 124 may measure the velocity or the change of velocityrelative to a predetermined distance threshold. In one example, thecontroller 124 may measure a predetermined velocity of the movableplaten 120 when about eighty percent compression of the initialthickness (without any load being applied) is reached. Once threshold isachieved, the controller 124 will control the audible alarm to signalthe surgeon that the optimal amount of compression has been achieved andthe surgical element should be applied to the tissue to join the tissuesections to one another.

In a further embodiment of the present disclosure, the movable platen120 and the stationary platen 122 of the device 100 have a predeterminedgeometry that is complementary to the end effector geometry of theinstrument used in the procedure. In one embodiment, where the surgicalelement is a surgical staple made from a biocompatible material such astitanium, the movable platen 120 and the stationary platen 122 have acompression area that is the same as the jaws of a surgical stapler.

Referring now to FIGS. 8 through 13, there is shown another embodimentof the present disclosure. In this embodiment, the method has the stepsof measuring an initial thickness of tissue. Thereafter, the tissue iscompressed with a device 200 and a final thickness of tissue at aphysiological response is taken. This final thickness is used tomodulate one or more parameters of the surgical procedure. FIG. 8 showsa modified caliper device 200 having a first caliper arm 202 and asecond caliper arm 204 defining a tissue gap 206 between the firstcaliper arm 202 and the second caliper arm 204. The caliper device 200also has a sensor 208. The sensor 208 is an optical or resistive elementto indicate visually, or audible that the device 200 is contactingtissue.

The caliper device 200 on an opposite end has a threaded arm 210 with anactuator 212 that is connected to the caliper arms 202, 204, and thatpermits the surgeon to manually rotate the actuator 212 to draw thefirst caliper arm 202 to the second caliper arm 204 with the tissuedisposed between the first and second caliper arms 202, 204 in the gap206. The caliper device 200 also can have an indicator or screen 201that visually indicates the thickness of the tissue such as a manuallywith a dial, or digitally with a LED, or display screen. The screen 201may be a liquid crystal digital display showing the unit of measurement.Alternatively, the screen 201 can be a conventional analog display ordial showing units of measurement in inches or millimeters.Alternatively, the caliper device 200 may be connected to an analog todigital converter to convert an analog signal to a digital signal tocommunicate the thickness electronically to the controller 124.

In this embodiment, it is envisioned that an optimal amount of strain ontissue is required to mechanically control bleeding and is desired toimprove surgical outcomes. It should be also appreciated that apredetermined amount of strain applied to tissue is known. Thispredetermined amount of strain will collapse the blood vessels topromote hemostasis. However, this predetermined amount of strain topromote hemostasis varies for different types of tissue.Gastrointestinal tissue, pulmonary tissue, abdominal tissue, colonictissue or small intestinal tissue may react differently and requiredifferent amounts of strain for each of the specific tissue types toensure a positive surgical outcome.

Compression is defined as the percent change in tissue thickness asshown in the following equation:

$ɛ = \frac{h_{f} - h_{i}}{h_{i}}$

Where (ε) is the strain, (h_(i)) is the initial tissue thickness, and(h_(f)) is the final tissue thickness after compression. Thus, dependingon the original thickness of tissue various different strains can beapplied to the tissue depending on the tissue type to ensure a positivesurgical outcome. In one embodiment, a minimum amount of strain can berequired to promote hemostasis, as well as, heal the tissue.

Referring now to FIG. 9, in this embodiment, the caliper device 200measures an initial thickness of the tissue T. In one embodiment whereanimal small intestine tissue T is being operated upon, the method hasthe step of determining an initial thickness of the aligned two tissuesections as shown in FIG. 9. One should appreciate that any desiredunits shown on the display 201 may be centimeters, or inches so long asthe measurements are taken in the subsequent procedures with the sameconsistent units.

Referring now to FIG. 10, the method next has the step of compressingthe two tissue sections together using the caliper device 200 from theinitial thickness to a compressed thickness to determine a secondthickness. The second thickness is a thickness at the occurrence of somephysiological event. In one embodiment, the physiological event is ahemostasis or the stoppage of bleeding from the tissue. This secondthickness is measured using the caliper device 200 by slowly releasingthe tissue section T from the first and second caliper arms 202, 204until a visual inspection of the two tissue sections T can be made at afinal thickness.

It is envisioned that the final thickness is the recorded thicknesswhere a visual inspection of a physiological response or event occurs.The visual inspection of a physiological response is, in one embodiment,the presence of a fluid, or blood traversing through the tissue.However, the present method is not limited to simply observing ahemostasis of tissue. Examples of other physiological responses includepartial hemostasis of the tissue, leakage of a fluid from the tissue,blood leakage from the tissue, or a complete healing of the tissue whenthe predetermined amount of compression from the device, (or anotherclamp is applied to the tissue T), or a time period elapsed thereafter.

Referring now to FIG. 10A, there is shown a graph of various differentstrains for several different tissue types. FIG. 10A is derived from theplot of shows strain applied to several different tissue types includinglung tissue, colonic tissue, stomach tissue, and small intestinaltissue. FIG. 10A shows the small intestinal plot generally indicated as“small”. The values indicate that in this particular non-limitingembodiment the tissue is being compressed. The y-axis shows in FIG. 10Athe optimal percentage or amount of compression that is determined fromthe initial tissue thickness. This percentage thickness is recorded atthe point of compression when the presence of blood at the cut edge ofthe transected tissue was observed in a test study. It is envisionedthat to create hemostasis for gastrointestinal tissue a strain range ofabout 60 to 80 percent is acceptable as multiplied by the initialuncompressed measured thickness. It is further envisioned that to createhemostasis for small intestinal tissue a strain range of about 60 to 70percent is acceptable. It is envisioned that to create hemostasis forstomach tissue a strain range of about 65 to 75 percent is acceptable.It is also envisioned that to create hemostasis for colonic tissue astrain range of about 70 to 80 percent is acceptable. It should befurther appreciated that pulmonary tissue is found to be significantlysofter than other tissue types. Because of the specific properties ofthe pulmonary tissue the percentage of compression required to achievetissue hemostasis is observed to be greater relative to other tissuetypes (such as abdominal tissue, or colonic tissue) as shown in FIG.10A.

It is envisioned that to promote tissue fusion in the sub mucosa sectionof tissue that a strain range of about 60 to 90 percent is acceptable.Generally, to create hemostasis for all tissue types a strain range ofabout 60 to 80 percent is acceptable as a general range. This generalrange is noted to promote a marked improvement to tissue fusion for alltissue types. However, various other factors such as tissue type, and/ortissue disease and the specific pathology of the individual patient mustbe taken into consideration in view of the general range.

For the purposes of explanation, the two tissue sections T will bediscussed in the context of an anastomosis procedure where the twotissue sections T are desired to be joined form a lumen. Care is broughtto such a situation so an optimal amount of compression is brought ontothe two tissue sections prior to the introduction of a surgical element,such as a stapler, or suture so as to avoid any leakage from the twojoined tissue sections which may leak into the another location of thebody such as the abdominal cavity.

Thereafter, in one embodiment, a pressurized source of fluid may also beapplied to the lumen or the tissue sections that are joined togetherwith the caliper 200. The caliper 200 is slowly released until theamount of blood or plasma escapes from the tissue. The tissue may befurther compressed, to determine a thickness at the hemostasis of thetissue. In this manner, the final thickness of the tissue at thephysiological response is measured at a peak force, or when thepressurized fluid flow occurs. In this manner, the final thickness ofthe tissue is recorded at the optimal compression for this particulartissue.

It is envisioned that only an optimal amount of compression is to beused with the various tissue types such as cardiovascular tissue,pulmonary tissue, abdominal tissue, colonic tissue, and/orgastrointestinal tissue. It is also appreciated that at no time does thecaliper 200 exceed the optimal amount of compression for a period oftime of about twenty minutes.

Based on the optimal final thickness and the initial thickness oftissue, various parameters of the surgical procedure can be determinedbased on at least the optimal final thickness and the initial thicknessof tissue. In one aspect, based on the final thickness of tissue, thesurgeon may use a clamping device that can clamp the tissue to thedesired final thickness prior to introducing a surgical element throughthe tissue. In another aspect, based on the final thickness of tissue,the surgeon may use a clamping device that can clamp the tissue to ageneral range of final thicknesses (during repeated usage) prior tointroducing a surgical element through the tissue such as about eightyto eighty five percent of the initial thickness prior to introducing thesurgical element.

It is also envisioned that based on the final thickness of tissue, thesurgeon may adjust the surgical instrument to compress the tissue to thedesired final thickness. In one embodiment, the surgeon may adjust apredetermined tissue gap measured between, for example, an anvil and acartridge of the stapler 10 shown in FIG. 9 for the application of thesurgical element through the tissue. This predetermined tissue gap maybe further altered for the optimal tissue compression. In anotherembodiment, the surgeon may adjust the surgical stapler 10 shown in FIG.9 to optimize a staple closure height of the stapler 10.

Referring now to FIG. 11, there is shown a compression montage of tissuehaving an initial thickness of 2.42 mm with a strain increment of 0.242mm per stage. FIG. 11 shows multiple zones where the compressive strainis increased about ten percent per stage with a strain increment of0.242 mm per stage until about 70 percent compression is reached. FIG.12 a shows the histology of the small intestine. It should beappreciated that the small intestine has a number of tissue layers or amucosa, sub mucosa, circumferential muscle, and longitudinal muscle.FIG. 12 a shows the small intestine tissue in the uncompressed orunloaded manner. FIG. 12 b shows the compressed tissue with the optimalamount of tissue strain.

It is understood that during the course of the optimal tissue strain ofthe tissue components, several factors come into operation prior to theapplication of the surgical element through the sections. First, fluidthat exists in the tissue will traverse away from the compressed site.Secondly, the tissue in some instances having an amount of tissuetherebetween will settle into an even or homogenized tissue restingstate. Third, will little or no blood supply to the compressed tissuesections, the tissue begins to soften. It should be appreciated that thetissue is compressed for an optimal period of time, but no longer ascompressing the tissue for periods of time in excess of the optimalperiod of time may lead to necrosis of the tissue. Whereupon, once thecompression is released the tissue will not decompress to its initialtissue state for homeostasis.

Referring now to FIG. 13 there is shown a schematic block diagramaccording to the present disclosure. The method commences at step 220.Thereafter, the method continues to step 222. At step 222, the methodhas the step of measuring the initial thickness of the tissue.Thereafter, the method continues to step 224. At step 224, the tissue iscompressed. In one embodiment, the tissue is compressed in a stepwisefashion as shown in FIG. 11 in increments. In another embodiment, thetissue may be compressed using the caliper device 200 of FIG. 8 in onestep. Thereafter, the method continues to step 226. At step 226, themethod reaches a decision block.

Here at step 226, the surgeon observes the physiological response of thetissue at the compression, such as hemostasis of tissue, the healing ofthe tissue, or leaking of fluid from the tissue to determine whether theoptimal amount of compression of the tissue has been reached. If thepositive response has been observed at step 226, then the methodcontinues to step 228 where the final thickness at the physiologicalresponse is recorded.

Thereafter, the method continues to step 230 where the surgical deviceis adjusted in a manner consistent with the final tissue thickness. Asmentioned, staple size selection can be changed in response to the finaltissue thickness, the gap between the surgical stapler and the anvil, oranother parameter of the instrument or procedure may be altered. At step226, where the method reaches the decision block and the surgeon doesnot observe any of the enumerated physiological response(s) from thetissue at the compression, this is indicative that the optimal amount ofcompression of the tissue has not been reached. If the negative responsehas been observed at step 226, then the method continues back to step224 to further compress the tissue at the next incremental amount suchas measured in millimeters. Once the instrument is adjusted, the methodterminates at step 232.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments.

What is claimed is:
 1. An apparatus for determining an optimal amount oftissue compression prior to the insertion of a surgical element into thetissue, comprising: a device for compressing tissue supporting ameasuring device adapted to detect a tissue parameter upon thecompression of the tissue, the measuring device communicating with anindicator; and wherein when the measuring device reaches a thresholdafter the tissue is compressed for a predetermined time period, themeasuring device sends a signal to the indicator such that the indicatorprovides an indication to the surgeon that the threshold has beenreached and that the surgical element is ready to be applied to thecompressed tissue, wherein reaching the threshold is indicative that thetissue has been compressed to a state wherein the surgical element canbe properly formed in the tissue at the indicated time period, andwherein when the compression is lifted after the threshold has beenreached, the tissue with the surgical element applied thereto returns toa substantially uncompressed state without necrosis.
 2. The apparatus ofclaim 1, wherein the measuring device is a load cell, the load celldetecting a viscoelastic reactive force of the tissue per unit time. 3.The apparatus of claim 2, wherein the device for compressing tissueincludes a movable platen and a stationary platen defining a tissue gapbetween the stationary platen and the movable platen, wherein the loadcell is adapted to be supported on the movable platen.
 4. The apparatusof claim 3, wherein the apparatus includes a controller connected to theload cell, the controller receiving data of the viscoelastic reactiveforce of the tissue per unit time, the controller comparing the data tothe threshold, the controller controlling the indicator upon reachingthe threshold.
 5. The apparatus of claim 4, wherein the threshold is aslope of viscoelastic reactive force of the tissue per unit time, andwherein the controller signals when the slope is indicative of optimalcompression of tissue.
 6. The apparatus of claim 5, wherein thecontroller signals the indicator when the slope has a negligible changeper unit time.
 7. A device for determining an optimal amount ofcompression of tissue to apply a surgical element, the devicecomprising: a body having a handle assembly connected to a shaft; a loadcell assembly having a load cell; a movable platen and a stationaryplaten connected to the shaft; wherein the movable platen is configuredto compress tissue against the stationary platen to apply a load to thetissue; wherein the load cell is disposed in contact with the movableplaten to determine a reactive load applied by the tissue in response tothe load; and a controller configured to determine the reactive load perunit time for a predetermined time period, wherein the controller isadapted to determine a slope of the reactive tissue load per unit time,and wherein the controller is configured to evaluate the slope relativeto a predetermined threshold stored in a memory, and the controller isconfigured to signal when the slope exceeds the predetermined threshold.8. The device of claim 7, wherein the load cell has a transducer adaptedto convert the load into a measurable electrical output.
 9. The deviceof claim 7, wherein the controller is dimensioned to be disposed in thebody.
 10. The device of claim 7, wherein the controller is disposedoutside the body.
 11. The device of claim 7, wherein the load cell is astrain gauge based load cell.
 12. The device of claim 7, wherein theload cell is a mechanical load cell.
 13. The device of claim 7, whereinthe movable platen is connected to a motor by a lead screw, the motormechanically advancing the movable platen in a direction toward thestationary platen to compress tissue.
 14. The device of claim 7, whereinthe movable platen and the stationary platen compress the tissue in apredetermined area, and wherein the predetermined area is complementaryin size to an area of tissue compressed between a surgical stapler anviland cartridge.
 15. The device of claim 7, further comprising a displayoperatively connected to the controller and configured to display thereactive load per unit time.
 16. A device for determining an optimalamount of compression of tissue to apply a surgical element, the devicecomprising: a body having a handle assembly connected to a shaft; a loadcell assembly having a load cell; a movable platen and a stationaryplaten connected to the shaft; wherein the movable platen is configuredto compress tissue against the stationary platen to apply a load to thetissue, and wherein the movable platen is connected to a motor by a leadscrew, the motor mechanically advancing the movable platen in adirection toward the stationary platen to compress tissue; wherein theload cell is disposed in contact with the movable platen to determine areactive load applied by the tissue in response to the load; and acontroller configured to determine the reactive load per unit time for apredetermined time period.
 17. The device of claim 16, wherein the loadcell has a transducer adapted to convert the load into a measurableelectrical output.
 18. The device of claim 16, wherein the controller isdimensioned to be disposed in the body.
 19. The device of claim 16,wherein the controller is disposed outside the body.
 20. The device ofclaim 16, wherein the load cell is a strain gauge based load cell. 21.The device of claim 16, wherein the load cell is a mechanical load cell.22. The device of claim 16, wherein the movable platen and thestationary platen compress the tissue in a predetermined area, andwherein the predetermined area is complementary in size to an area oftissue compressed between a surgical stapler anvil and cartridge. 23.The device of claim 16, further comprising a display operativelyconnected to the controller and configured to display the reactive loadper unit time.